One of the best tools that you have as gardeners to help us figure out your gardening schedule is the USDA zone info. The zone info helps tell us things like average date of last frost and lowest expected temperature for your area.

By referring to the USDA zone info for Gypsum you will be able to estimate when it's the best time to plant oenothera.

Planting Calendar for Oenothera

Frost tolerance for oenothera:	Tolerant of some frost.
When to plant:	Up to 5 weeks before last frost.

Oenothera do well in moderate cold which tells us that you can get them planted earlier than plants that are more sensitive to the cold.

The earliest that you can plant oenothera in Gypsum is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant oenothera and expect a good harvest is probably September. Any later than that and your oenothera may not have a chance to grow to maturity. Starting your oenothera indoors is a great way to get them started a little bit earlier.

Last Frost Date

On average the last frost has passed is on April 15 in Gypsum. In the coldest months of winter you should expect an average low temperature of -20°F.

Since the USDA zone info for Gypsum is just an average the actual date of last frost changes from year to year. Half of the time in Gypsum you get a frost after April 15 so make sure that you are prepared to cover your oenothera in the event of a late frost.

USDA Zone Info for Gypsum

Here is the info for USDA Zone 5a.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-20°F
Highest Expected Low	-15°F

This means that on a really cold year, the coldest it will get is -20°F. On most years you should be prepared to experience lows near -15°F.

Plants to Grow in Gypsum

You may be interested in your other planting guides for Gypsum.